1. Field of the Invention
The present invention relates to a dental centrifugal casting apparatus for casting an artificial tooth such as an artificial crown by using, e.g., glass ceramic as a casting material.
2. Description of the Related Art
Conventionally, metal materials such as a gold alloy and a nickel-chromium alloy have been used as a material for casting an artificial tooth such as an artificial crown. Melting temperatures of these metal materials fall within the range of 1,000.degree. C. to 1,100.degree. C., i.e., comparatively low. Therefore, a resistant-heating electric furnace has been used as a material heating/melting means for use in a conventional dental centrifugal casting apparatus. In order to cast an artificial tooth such as an artificial crown, the above material heated/melted in the electric furnace is flowed into an investment preheated at 400.degree. C. to 500.degree. C., and then a manual centrifuge is operated to perform centrifugal casting. That is, casting has been conventionally performed by such a simple manual operation.
In recent years, however, a glass ceramic material having good affinity to a living body is used as an artificial tooth material. A melting temperature of this glass ceramic material is about 1,300.degree. C. to 1,500.degree. C., i.e., much higher than that of the conventional metal materials. When a material having such a high melting temperature is used, cast products having uniform characteristics cannot be stably manufactured by the conventional manufacturing process since casting must be performed under strict casting conditions.
In order to solve this problem, various types of artificial tooth casting apparatuses improving the conventional manufacturing process have been proposed. For example, Published Unexamined Japanese Utility Model Application No. 60-166460 discloses an apparatus of this type. Such an apparatus, however, is generally large in size. In addition, a highly skilled operator is required to operate the apparatus of this type in order to cast a metal into an artificial tooth. That is this apparatus cannot be easily used for dental casting apparatus.